Discussing the article, "A Perspective on 3-D illusions" by Stephen L. Macknik and Susana Martinez-Conde

According to this article, it has been proven that what we believe to be seeing, is only but our imagination playing tricks on us. The reasoning for this is because strangely our real and imagined thoughts/perceptions are using the same part of the brain. So, our real senses, or what we believe to be our real senses, are using the same neural system that our dreams, delusions, and failed memories are using. A way that neuroscientists study how our brain perceives the physical world is by using illusions. Many illusionists or realists, as they like to call themselves, use a certain method or way to make a 2-D painting look 3-D. They use perspective, lighting, color, and shadow to add depth to the canvas and make the painting “pop out” and difficult to distinguish if it is real or not. Illusions cause people to think something is there that isn’t, think something is actually something else, or miss something entirely. These figments of our imagination, trick us to question our brain and how it comprehends the world around us. However, scientists use these faults to study the computational methods our brain uses when we encounter illusions or the environment in general.

Not only does our brain trick us when we look at 2-D imagines, but it can trick us when we are looking at 3-D objects in 2-D as well. A popular example is the Leaning Tower of Pisa Illusion that was discovered by three McGill University students when they put two of the same pictures of the tower next to each other. The illusion is that even though it is the same picture, the towers look like they are leaning at two different angles. This deception occurs because our visual system does not know anything about our three dimensional world and must rely on our depth perception. According to the article, our depth perception includes specific rules such as, “perspective (parallel lines appear to converge in the distance), stereopsis (our left and right eyes receive horizontally displaced images of the same object, resulting in the perception of depth), occlusion (objects near us occlude objects farther away), shading, chiaroscuro (the contrast of an object as a function of the position of the light source) and sfumato (the feeling of depth created by the interplay of in- and out-of-focus elements in an image as well as from the level of transparency of the atmosphere itself)”.

I think how our brain sees the world every day is very interesting. We believe what we see is real and use that as proof in situations because we “saw it with our own two eyes”. However, according to this article and many illusions, our eyes and what we see isn’t always that reliable. So next time you’re walking down the street and see a staircase, make sure it isn’t a painting on a door so you don't stupidly run into it.